The invention relates to an axial piston machine. It relates particularly to such a machine having a tiltable cylinder block and a socket plate rotated in fixed bearings in the body of the machine by a drive shaft. Pistons are operatively coupled with the socket plate by ball and socket joints, and a valve plate is adapted to be displaced by stroke control mechanism in a cylindrical slideway which supports a conformably shaped back of the valve plate facing away from the cylinders. The sides of the valve plate are guided between side faces in the body of the machine which prevent displacement in the direction of the axis of tilt.
Axial piston machines of the specified kind are particularly suitable for compact self-contained transmissions, and in service they excel by their silence and freedom from vibration, even when the pressures and speeds of rotation are high.
In a machine of such a kind it has been proposed (German published Patent Specification No. 1,017,468) to provide the valve plate with surface areas and grooves where the hydraulic pressure is used to balance the tilting moment which acts on the cylinder block and which is transmitted thereby to the valve plate. Moreover, for stabilizing the valve plate its sides are provided with faces supported by rollers. It is a defect of this arrangement that whenever the cylinder block is tiltably moved, particularly when this is done under load, the forces acting on the valve plate may cause the latter to become misaligned and wedged between the lateral support means in the body of the machine.
In order to guard against this result it has been proposed (U.S. Pat. No. 3,233,555), in an axial piston machine having a cylindrical concave slideway, to support the sides of the valve plate by balls and through the agency of the balls to apply an additional lateral force which depends upon the magnitude of the end thrust to the sides of the valve plate so that the side faces of the plate are yieldingly held.
However, both the above mentioned arrangements have the drawback that either the valve plate must be of major dimensions or that supplementary means must be provided to prevent the valve plate, when the cylinder block is being tilted, from becoming jammed between the lateral guiding faces by the action of the torque which is applied to the valve plate by the rotating cylinder block.
In an axial piston machine having a tiltable cylinder block and an adjustable cradle it has been proposed (Swiss Patent Specification No. 325,587) to support the valve plate either in a cylindrical slideway or on a spherical surface inside the body of the machine. However, the arrangement described in this specification lacks means for laterally guiding the valve plate which can adjust itself freely on the spherical surface. The problem of jamming by wedging between lateral guide means does not therefore arise with such a non-guided valve plate construction.